US3542130A - Valve for removing paraffin from oil wells - Google Patents

Description

latexted Nov. 24, 197

Irw AV IEA/TOR. DON W. STOUT MARCUS L. BATES United States Patent "MII,l

U11 3,542,130 [72]V Inventor Don W. Stout 2,4l |,O44 ll/l946 Landrum et al. I66/4IX 0dllsa,'l`xls 2,593,520 4/1952 Baker et al l66/l94 [2l] Appl. No. 717,778 3,085,629 4/I963 Henderson l66/224 (22] Filed Aprll l, i968 3,126,965 3/l964 Lindsey l66/224X [45) Patented NM' 24 1970. i Pri'mar Examiner- David H. Brown [73] Assignee v :Finn Tool and Eqiilpment Company, Atwm MarcuS L Bates Odessa, Terms M ABSTRACT: A valve means placed in series with a string of [54) VALVE FOR REMOWNG PARAFFIN FROM OIL pipe which vertically depends into an oil well, wherein the WELLS string of pipe is used for conducting fluid into the vicinity of 3 claims. 5 Draw." man. the production formation The valve means includes a barrel having radially disposed ports formed therein with the barrel [52] U-S. Cl. 166/224, formmg a part of the stl-mg of pipe An dongated honow awe 156/304 element is reciprocatingly received within the barrel with the [5l] llll.c|.....,.i..` ........,.......E2lb43/00 honnw passageway [hereof being tapered A dlssolvable [50] Field ofSearcli l66/40, 4l, member smh as d wax plus ,s circulated down the plpe where |05, l07, |54, |94, l77,224, 304; l75/237 it is received within the tapered hollow passageway. thereby A causing the valve element to be forced in a downward [56] References cned direction for a limited distance. This action uncovers the radi- UNITED STATES PATENTS v al ports and allows fluid such as hot oil to be circulated a 2,224,538 l2/l940 Eckelet al. l66/l94X predetermined distance down the pipe .md back up the annu- 2,300,348 l0/l942 Dana l66/40 lus between the casing and the pipe. The accumulated paraffin 2,307,983 l/l943 Barnes l66/ l54X along with the plug eventually dissolves, leaving the valve 2,312,789 3/l943 Applebyl l66/l94X body, casing, and pipe free from any obstruction.

, l VALVE ronREMoviNc PARArriN Fnolvi orL WELLS BACKGROUND or THE INVENTION f In the production of oil from an oil well, sometime"v the crude oil contains a high wax cir-'paraffin content, The production zone of the oil well is usually at a higher temperature4 than ambient, sometime by an amount exceeding 250F. Cone the well wherein the treating fluid is bypassed from the central sequently, as the oil is pumped or otherwise produced from the well is restricted as the wax builds up in thickness, and eventually production becomes uneconomical or impossible due to the normal flow path of the produced oil being obstructed by the wax formation. Since the deposition of the wax may occur anywhere between thewell head and the producingiormation, the obstruction is sometimes located several thousand feet below theisurfac'e of the ground. l

Various treatments including chemicals andsolvent's have been employed in removing the accumulated paraffin.` An ex cellent low cost solvent is heated crude oil; or hot oil. ln usinghot oil for the removal of the .accumulated wax, the hot tubing into the annulus. It is further contemplated to use various configurations of the soluble plug which activates the valve element, such as a ball, for example. The composition-of the plug can be selected from various known materials which are soluble in hydrocarbons so as to provide any desired time lapse for the paraffin removing operation. Accordingly, it is a primary object of the present invention to provide a method of removing paraffin from an oil well.

Another object of the present invention is an improved circulation pattern for removing paraffin from oil well.

A still further object of the present invention is to provide a method of removing paraffin frornan oil well by utilizing a meltable or soluble plug in order to control the circulation pattern of treatingfluids. I n Still another object of the present invention'is the provision of apparatus for controlling the flow pattern of fluid which is pumped down the tubing string of an oil well.

Another object ofthe present invention is the provision of a valve means kwhich can be connected in series relationship within the tubing string of an oil well to thereby permit the flow pattern of the well to be controlled by a meltable and/or y soluble plug.

oil is pumped downhole through the annulus, andback up the I inside string, or down and through the pump and back upthe production string, whereupon circulation of the oil through a heater eventually causes the wax tobe dissolved, thereby freeing the casing from the obstruction. This operation can be peryThe above objects are attained in accordance with the present invention by the provision of method and apparatus which permits a soluble or meltable plug to be pumped through the central tubing of an oil well whereupon the plug actuates a valve means to thereby establish a predetermined flow path through the well.

'These and other objects of the invention will become apparent to those skilled in the art as the description proceeds.

formed by providing a flow path for the heated oil which ini cludes breaking down the tubing so as to expose the'terminal end thereof whereupon the hot oil can be flowed down the tubing and back 'up the annulus between the tubing and the casing.

vsuivit/Irun(or THE INVENTION y An improved'crculation pattern-forl removing-.paraffin or wax from oil wells by providing a slidably valve element having a tapered passageway therethrough whereinthevalveelement forms part of the normal f low system ofan oil well. The

oil well includes a casing having a central tubing located therein, with the tubing being'connected to a downhole pump.

The valve element is enclosed by. 'a barrel which is threadedly connected at each depending end to the existing tubing.-The valve element is spring'bi'ased inanv upward direction and. reciprocates for a limited distance within the barrel. A` multiplicity ofradial ports are formed in thewall surface of the barrel, with the port holes being normally sealed against flo'w by the valve element. A meltable and/or soluble plug can be placed in the central tubing and circulated downhole until it lodges within the tapered passageway of the valve element, whereupon thepress'ure exerted upon the plug and'element by the .circulating oil forces the valve element to move downwardly until vits upper, extremity uncovers the,l radial ports, thereby permitting oil to flow from the tubing into the annulus described by the tubing and casing and backto the surface of the ground. The composition of the plug is selected from a material such as wax which enables sufficient lapse 'of treatment time'to occur before the plug melts or dissolves.

This time delay enables the hot oil to completely dissolve all of 4thedeposited paraffin from the interior of the casing.` Upon completion of the removalof wax from the casngythe hot oil temperature and pressure is increased whereupon the plug is extruded in a downward direction `vthrough Athe tapered passageway of the valve element. Since the plug is soluble in hydrocarbons it eventually melts or dissolves whereupon normal operation of the well can be resumed.

While the present invention has been exemplified by using hot oil as the'l solvent, it should be understood that the use of other paraffin removingfluids is contemplated, aswell asthe use of the present invention in carrying out any treatment of BRIEF DESCRIPTION OF THE DRAWINGS part of theapparatus seen in FIG. 1; l FIG. 3 is a cross-sectional View taken along line 3-3 of FIG.

'FlG.-4 isa fragmentary cross-sectional representation of part Vof the xapparatus seen in FIG. 2 but with the apparatus being shown in the bypassing position; and

FIG. 5 is a cross-sectional view taken along line 5-5 of FIG.

v4, with additionaipans beinggshown.

DESCRIPTION OF THE PREFERRED EMBODIMENT Looking now to the details of the drawings there is seen schematically*illustrated in- FIG. 1 a bore hole l0 located below-the surface of the ground 12 and which extends into an oil bearing stratum 14. A casing 16 having a topmost portion 18 from which the produced oil flows at 20 is included therein. l

Inlet conduit 22 and outlet conduit 24 are valved to the centrally located tubing 26 with the tubing continuing downhole as seen at 28 to a means for lifting oil, as generally indicated by the arrow at numeral 30.

A valve bypass means y32 is series connected between the tubing 26 and 28 by means of subs 34 and 36.

Looking now to the details of the valve bypass means which is set'forth in detail in FIG. 2 in conjunction with the remain- 'ingFIGS., thereV is seen disclosed therein a barrel 37 having upper threads 38 and lower threads 40 which threadedly receive the before mentioned subs.

The inside peripheral wall surface of the barrel at 42 is polished and extends from the shoulder 44 formed by the upper sub to the shoulder 46 formed by the lower sub. A valve element 48 has an upper terminal end 50 which abuts against the before mentioned upper shoulder, and a'lower terminal end 52 which abuts against the lower shoulder. The valve element has a contoured passageway extending therethrough with the passageway being downwardly converging as seen at 54 where it converges into passageway 56 which may be of constant diameter. Spaced apart upper and lower pairs of grooves 58 and 60 respectively, receive the illustrated o-rings therein which seals the outside peripheral wall surface of the valve element to the inside peripheral wall surface of the barrel to thereby preclude fluid flow therebetween.

The downwardly depending tubular portion 62 of the valve element is reduced in outside diameter to thereby leave a shoulder 64 which defines the uppermost portion of the annulus which extends between the downwardly depending portion and the barrel so as to freely accommodate spring 66 therein. The spring is illustrated as being compressed between the before mentioned shoulders 46 and 64.

Radially spaced apart ports 68 communicate the inside of the barrel with the inside of the casing when the valve element is actuated. lt should be noted that ample space is provided between the lower terminal end portion 52 and shoulder 46 so as to permit the upper terminal end 50 to be forced below the ports in a manner as illustrated in FIG. 4.

A soluble or meltable plug 70 having a diameter which enables it to be received within the upper portion of the valve element is partially received within the tapered portion 54 to thereby effectively plug the central passageway of the valve element in a manner as set forth in FIG. 4.

OPERATION ln operation, the embodiment illustrated in FIG. 1 is shown in conjunction with a downhole hydraulic pump 30, such as a Kobe pump, wherein power fluid is supplied at 22, with the power fluid flowing down the central tubing 26, 28 to the engine of the pump whereupon the power oil is comingled with the produced oil and pumped back up the annulus between the tubing and the casing where the oil flows through outlet and into the gathering system. Upon casing 16 becoming partially obstructed due to an accumulation of precipitated or deposited paraffin on the inside peripheral surface thereof, hot oil is circulated down through the tubing 26, through the valve bypass means 32 and back up through the outlet 20, thus bypassing the pump which is deenergized due to the configuration of the valve. After the hot oil has dissolved or melted the accumulated paraffin from the annulus, the bypass valve is returned to its normal position and production is resumed in the usual manner.

ln carrying out the about above described operation', the valve bypass means 32 is preferably connected in series with the central tubing 26, 28 by means of the illustrated upper and lower subs, although the tubing could be directly screwthreaded into the barrel if desired. When the circulation is being carried out with the system in the normal production configuration, the valve bypass means will be in the illustrated configuration of FlG. 2 wherein power oil from tubing 26 flows through sub 34 and into the central passageway of the valve element where the flow continues through the downwardly converging portion 54, through the constant diameter portion 56, through sub 36, and on to the downhole pump by means of tubing 28. During this time of normal operation the pressure drop across the valve bypass means is insufficient to cause movement of the valve element due to the pressure ofspring 66.

When the power oil pump or other components of the system indicates that paraffin has built up a noticeable amount so as to justify treatment of the well, the power oil pump is deenergized and a hot oil system is connected to tubing 26. The soluble plug 70, preferably of wax which will dissolve in oil` is dropped into the tubing 26 and circulation of the hot oil commenced` Since the diameter of the soluble or meltable plug enables the plug to be received within the upper terminal end ofthe valve element, but precludes passage of the plug through the converging section, the plug and valve bypass means is accordingly forced into the configuration of FlG. 4 due to the pressure differential across the valve bypass means. This cooperation between the plug and the valve element enables the valve element to act much like a piston within a cylinder, whereupon the valve element is sldably forced against the spring and into the configuration of FlG. 4, where it will be maintained so long as the pressure of the hot oil is sufficient to overcome the tension of the spring 66. Circulation of hot oil now follows along the path described by tubing 26, sub 34, and through the radial ports of the barrel whereupon the flow now returns to the surface by means of the annulus between the tubing and the casing.

ln carrying out the above described operation, after the meltable plug has been inserted into the tubing 28, the hot oil pump begins circulating oil into tubing 26 and out of the outlet 20 assuming thecasing to be full of oil, The system can be monitored by a pressure gauge located at 22 or 26 which will abruptly change in pressure upon the plug initially lodging within the valve element, and will soon attain equilibrium after opening ports 68 as the hot oil is bypassed into the casing. Circulation continues with the hot oil being supplied to the valve bypass means until the well is free of paraffin. A knowledge of the history of the well, together with the pressure readings will enable one skilled in the artto determine when the casing is free from paraffin.

The meltable plug will be partially dissolved during the treatment of the well, and it is preferable that at end of the operation, that is, after the paraffin has been completely removed from the casing, there will still be a sufficient amount of the meltable plug remaining in the converging section of the valve element so as to maintain the valve in opened or bypassing configuration. The pump pressure is now increased whereupon the plug is forced completely through the passageway of the valve element and into the tubing string 28.v

The hot oil system is next removed from the well head and the well is left dormant for a sufficient length of time which will assure that the meltable plug completely dissolves before production is resumed, otherwise the undissolved plug will be forced into the pump mechanism.

As soon as the meltable plug has been forced from the valve element, spring 66 urges the valve element back to the normal position of operation seen in FlG. 2, thereby closing ports 68. Spaced apart upper and lower seals prevent leakage from the tubing into the annulus during normal operation.

Should the plug be left within the valve element, or should the plug inadvertently be forced into the downhole pump mechanism, the plug will ultimately be dissolved by the power oil during the time in which the well is left dormant.

While the present invention has been exemplified by using hot oil as the solvent, it should beunderstood that other paraffin removing fluids are contemplated, as well as carrying out any treatment of a well wherein the treating fluid is bypassed from the central tubing into the annulus. lt is further contemplated to use various configurations of the soluble plug which activates the valve element, such as a ball, for example. The chemical composition of the plug can be selected from various known materials which are soluble in hydrocarbons so as to provide any desired time lapse for the paraffin removing operation. Accordingly, the meltable or soluble plug 70 can be any plug which offers sufficient resistance to the flow of hot oil in order to upset the valve element, and which will also completely dissolve in oil over a known period of time.

While l have illustrated and described a preferred embodiment of my invention it is to be understood that such is merely illustrative and not restrictive and that various modifications may be made therein without departing from the spirit and scope of the invention. l therefore do not wish to be limited to the precise details set forth but desire to avail myself of such changes as fall within the purview of my invention.

I claim:

l. ln an oil well having a casing, a down hole pump corinected to a power oil source through a tubing string located in the casing wherein produced fluid flows from the pump and up through the annulus formed between the tubing string and the casing, in combination:

a bypass valve means adapted to be series connected in the tubing string for normally flowing fluid to the downhole Pump:

said` bypass valve means including abat-rel and a valve element with said valve element being movable from a first to a second position; means forming a main flowpassageway through said valve element for flowing fluid to the p ump when the valveelement is in the tirst position;

means forming a bypass flow passageway through said barrel for flowing fluid into the annulus when the valve element is in the second position; and v a dissolvable plug, said plug being smaller in size than the inside diameter of the tubing, and largerrin sizvefthan said main flow passageway, to thereby permit said plug to be circulated down the tubing` string, to the bypass valve means, whereupon the valve element is moved from said first to said second position, to thereby cause'tluidto flow from the tubing string, through said bypass flow passageway, and intol the annulus while flow is precluded .downhole to the pump.

said bypass flow passageway including spaced apart radially disposed ports; whereby:

when said valve element is in the first position. said ports are covered by the outer peripheral wall surface of said valve element; and

when said valve-'element is moved to the second position said ports communicate with the interior of the tubing string.

3. The combination of claim 1 wherein said barrel includes l an' elongated cylindrical passageway;

l2. The combination of claim l wherein said barrel includes v through said valve element to thereby form said main flow passageway;

said valve element being an elongated piston slidably received within said cylindrical passageway;

means forming a longitudinally disposed passageway through said valve element which forms said main flow passageway;

said bypass flow passageway including at least one radially disposed port; andv said ports are covered by the outer peripheral wall surface 4of said valve element when said valve element is in the first position, and. when said valve element is in the second position, said ports communicate with the interior of the tubing string which is uphole of the bypass valve means.4

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